Use DiskWarrior's Scavenge mode

Many people, myself included, rely on
DiskWarrior
to fix drives that have otherwise become unusable. In my particular case, I had a bad FireWire hub (unbeknownst to me) that was causing my FireWire drives to routinely go into never-never land. DiskWarrior (
;
October 2003
) would then come to the rescue, rebuilding the damaged directory structure and returning the drive to a usable state—almost always without any data loss. Needless to say, DiskWarrior is a key product in my Mac’s first aid kit.

DiskWarrior normally scans directories, focusing its attention only on damaged portions of the directory structure. This makes sense, for if a given portion of the directory isn’t damaged, then there’s no need to repair it. But in some cases, you might want DiskWarrior to go ahead and scan the apparently-healthy directory information as well. Just what cases, you ask?

Assume you have some other disk repair tools in your machine’s first aid kit, and you tried some of them before running DiskWarrior. It’s possible that the other tools were able to repair the directory damage, leaving no damage for DiskWarrior to find. But it’s also possible that the repaired directory structure may not find all your stuff—so you’ve now got an apparently healthy directory, but you’re confident there are some files and folders missing.

This is where DiskWarrior’s Scavenge mode comes into play. If you hold down the Option key in DiskWarrior’s window, the Rebuild button changes to read Scavenge. In Scavenge mode, DiskWarrior will look at the entire directory structure, not just those portions that are damaged. Note that the technique used in Scavenge is the same as that used in Rebuild; it’s just that all of the directory is examined. As such, you only need to use Scavenge when the disk’s directory is fine, but you suspect that there’s data missing. As explained in the DiskWarrior manual:

Therefore, you do not need to make DiskWarrior scavenge the directory except when DiskWarrior states “All file and folder data was easily located” in the DiskWarrior Report, but you suspect that files and/or folders are still missing from the replacement directory.

I personally haven’t had the chance to test the Scavenge mode yet, but I’m glad to know there’s a way to force DiskWarrior to work with the entire directory.